Lots of new thermal components, engine decks, updates for new OpenMDAO, and more

[eytanadler]

Purpose

This PR adds a host of new thermal components including an improved refrigerator, heat pipes, and flow splitters. It also includes engine models for the CFM56, a representative N+3 turbofan, and a parallel hybrid N+3 turbofan. Many components have been updated to function better with more recent versions of OpenMDAO and more unit/regression tests have been added.

Type of change

What types of change is it? Select the appropriate type(s) that describe this PR

• New feature (non-breaking change which adds functionality)
• Documentation update

Testing

Explain the steps needed to test the new code to verify that it does indeed address the issue and produce the expected behavior.

Checklist

Put an x in the boxes that apply.

• [x] I have run unit and regression tests which pass locally with my changes
• [x] I have added new tests that prove my fix is effective or that my feature works
• [x] I have added necessary documentation

[coveralls]

Pull Request Test Coverage Report for Build 1391999426

• 1030 of 1540 (66.88%) changed or added relevant lines in 21 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.3%) to 86.147%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
openconcept/analysis/trajectories.py	44	45	97.78%
openconcept/components/cfm56.py	3	5	60.0%
openconcept/components/heat_pipe.py	201	203	99.01%
openconcept/components/heat_exchanger.py	11	14	78.57%
openconcept/components/ducts.py	155	160	96.88%
openconcept/utilities/dict_indepvarcomp.py	3	21	14.29%
openconcept/components/heat_sinks.py	251	273	91.94%
openconcept/utilities/visualization.py	1	41	2.44%
openconcept/analysis/performance/dymos_phases.py	0	152	0.0%
openconcept/components/N3.py	75	340	22.06%
<!--	Total:	1030	1540	66.88%	-->

Totals
Change from base Build 611745095:	-1.3%
Covered Lines:	4546
Relevant Lines:	5277

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💛 - Coveralls